1. Field of the Invention
The present invention relates to a filter assembly and a device for reducing an exhaust gas including the same. More particularly, the present invention relates to a filter assembly including an electrode unit having an improved structure for preventing obstruction of flow of the exhaust gas introduced into a filter, and a device for reducing an exhaust gas including the same.
2. Discussion of Related Art
Compared to a gasoline engine, a diesel engine has advantages in terms of fuel-efficiency and output. Unlike the gasoline engine, however, the diesel engine discharges harmful substances such as particulate matter (PM) in its exhaust gas.
Since such particulate matter has been recognized as a major form of air pollution, many countries have tightened their regulations on the discharge such harmful substances.
In order to satisfy the regulations of every country on the discharge of harmful substances such as particulate matter, technologies for reducing harmful substances have been developed. As technology for reducing harmful substances such as particulate matter, a diesel particulate filter is mounted on an exhaust gas flow passage between the diesel engine and a muffler to capture particulate matter.
Here, the filter captures particulate matter discharged together with the exhaust gas. As a method of recycling particulate matter captured by the filter, the filter is directly heated to burn particulate matter captured on the filter.
For example, an electrical heater or a diesel burner is installed between the engine and the filter, and a temperature of the exhaust gas is increased up to a temperature at which particulate matter captured in the filter can be burned. In order to heat directly the filter, an electrode unit to which electric power is applied to is connected to the filter.
However, installation of the electrical heater or the diesel burner between the engine and the filter reduces productivity. Accordingly, as another method, an electrode unit is directly connected to at least one surface of the filter. By the electrode unit connected directly to one surface of the filter as above, the filter is heated so that particulate matter captured in the filter can be burned.
Here, the problem with the filter utilizing the electrode unit is that some regions of the filter are blocked by a shape of the electrode unit.
On the other hand, the above conventional method for directly heating the filter is disadvantageous in that the filter is cooled by a low-temperature exhaust gas flowing into it so that an excessive amount of energy is consumed to heat the filter. In addition, since the conventional filter has one capturing region, a lift of the filter is shortened due to over-heating or super-cooling of the heater.